Examples of eco-friendly vehicles that use electrical energy of batteries include electric vehicles, plug-in hybrid vehicles, and hydrogen fuel cell vehicles. The electric vehicle and the plug-in hybrid vehicle are supplied with power from a charging device provided in an external charging station to charge a battery. The hydrogen fuel cell vehicle is configured to convert hydrogen into electrical energy to charge a battery.
Internal combustion engine vehicles using gasoline or diesel can be easily supplied with fuel because gas stations for supplying gasoline or diesel are widely distributed. However, since the distribution rate of charging stations for electric vehicles, plug-in hybrid vehicles, and hydrogen fuel cell vehicles is very low, it is necessary to periodically check the amount of electricity remaining in a battery of the vehicle or the amount of hydrogen remaining in a hydrogen fuel tank while paying close attention to the resupply of electricity and hydrogen by monitoring the distance to empty of the vehicle.
In this regard, a function of displaying the distance to empty based on the remaining power of the battery or the remaining amount of the hydrogen to allow a driver to recognize the distance to empty is very important in an eco-friendly vehicle.
To this end, the eco-friendly vehicle displays the distance to empty (traveling range) based on remaining energy (electricity or hydrogen) on a navigation map so that the driver can easily recognize and refer to the distance to empty. However, when the eco-friendly vehicle is traveling, the position of the eco-friendly vehicle changes and the remaining energy also changes. Since the distance to empty (traveling range) is calculated again based on the remaining energy whenever the position of the eco-friendly vehicle changes and displayed on the navigation map, the computation time and graphic processing time may become longer due to a large amount of computation, so that the distance to empty (traveling range) of the vehicle is not immediately updated on the navigation map. Due to such a delay, the distance to empty of the vehicle cannot be updated in real time on the navigation map. For this reason, the marketability of a navigation system or the eco-friendly vehicle may be degraded.